Dunlavy Audio Labs SC-IV/A loudspeaker Manufacturer's Comment

Manufacturer's Comment

Editor: Once again, what can we say—the Stereophile review by Robert Deutsch and John Atkinson of our new SC-IV/A loudspeaker seems to have said it all!

RD's perceptions and descriptions of the relatively small but important audible differences between our standard SC-IV and the new SC-IV/A loudspeakers certainly characterize him as a reviewer possessing an uncommon ability to accurately assess and describe such differences.

Indeed, we at DAL feel honored by RD's final observation: "Remember the frog whose jumps always take him halfway toward his goal? Audiophiles and audio manufacturers are much like that frog, approaching but never quite reaching the goal of perfect fidelity. Or, as Paul Simon put it, 'The nearer your destination, the more it keeps slidin' away.' With the SC-IV/A, Dunlavy Audio Labs has managed the feat of jumping more than halfway toward the goal. Very simply, this refinement of the SC-IV/A has reached the point where—with the best source materials and associated equipment—it sounds less like a speaker and more like the music that's being reproduced."

We are equally indebted to John Atkinson for his measurements of the SC-IV/A, but only wish that Stereophile possessed a more extensive array of laboratory test equipment and a large anechoic chamber. Such a facility is necessary because loudspeakers having the physical size of the SC-IV/A must be measured "anechoically" at the normal listening distance of 10' if the measurements are to convey any relevance as to how accurately they will reproduce complex musical sounds and transients in a typical listening room.

For example, we measure loudspeaker performance at a distance of 10' in one of our two 24' long by 20' wide by 16' high anechoic chambers (accurate to within ±0.1dB above about 200Hz). In our chambers, the SC-IV/A yielded an on-axis frequency response of ±1dB (without "smoothing," etc.) compared to JA's measurements, which showed ±1dB variations at distances up to about 100" (within a nonanechoic room environment, replete with reflections). Likewise, JA's measurements of impulse response and step response (at 50") hardly portray the loudspeaker's nearly "textbook-perfect" performance as seen from DAL's measurements.

Further, since few audiophiles are likely to listen to loudspeakers the size of the SC-IV/A at only 50", we believe that our measurements provide a much more accurate indication of how they will sound in a real listening room at the average listening distance of 10'.

Likewise, although the SC-IV/A reproduces squarewaves with an accuracy that would make many top-of-the-line tube amps blush, this was not verified by John's measurement of a 500Hz squarewave at a distance of only 50", in a room having obvious reflections. This is regrettable, because we believe that the SC-IV/A, and several other DAL loudspeaker models, may be the only loudspeakers presently available that can perform such a feat.

It should be mentioned, however, that John's measurement capability may be quite adequate for assessing the properties of loudspeakers having smaller dimensions than those of the SC-IV/A. This would hold for loudspeakers whose driver separations are small with respect to a wavelength and/or the distance of the measurement. This problem is somewhat related to the distance over which a camera lens of large diameter can remain in focus. In this context, an array of loudspeaker drivers also exhibits both "focal distance" and "depth-of-field" properties.